Printing machine systems in which a printing couple can be stopped while another printing couple continues to operate usually are so arranged that a specific printing couple is used to print a continuous, unchanged text, while another one is used in which exchange of the plate is possible. At least two, alternately connectable printing couples are required if a change in the text to be printed is desired. This permits preparing one plate cylinder, which has just been discontinued or stopped, with a plate for the subsequent, changed text, whereas the other couple continues to print the desired text. Clutches permitting alternate operation of the printing couples for a system of this type are well known in the industry and described, for example, in U.S. Pat. No. 4,346,656, to which No. 28 44 418, corresponds.
It is necessary that the plate cylinder and all apparatus coupled thereto print with proper circumferential as well as lateral register and, therefore, it is customary to provide arrangements for circumferential and lateral register of the plate cylinders. The clutch arrangement of the U.S. Pat. No. 4,346,656 does not, however, concern itself with register adjustment arrangements.
In order to control register, it has been known for many years to shift the circumferential position of one cylinder with respect to another by engaging spiral gears coupled to the respective cylinders, and axially shifting the respective cylinders relative to each other, see for example German Pat. No. 415,380, assigned to a predecessor company of the applicant of the present application, and published in 1925. In order to maintain the register of such coupled cylinders, the cylinders are supplied with special register control gears which, however, are not used to drive the respective cylinders; they are only to maintain circumferential relative position.